Penn State News / Research Update

By Nathaniel Leiby (BS ’18, current MS AGRO candidate) and Max Schlossberg, PhD., Penn State University Center for Turfgrass Science

Ammonia volatilization of foliarly-applied nitrogen (N) fertilizer from turfgrass is deleterious to both the environment and the original agronomic objective. Current BMPs mitigate some loss, but circumstances specific to putting green and fairway management often preclude their implementation. Our research objective is to quantify how foliar application of commercially available petroleum-derived spray oil (PDSO), Civitas PreM1xed (8.5 oz. per 1000 ft 2 ), and/or urea-based N influences canopy quality, and fertilizer-N recovery or loss from creeping bentgrass putting greens and fairways. To quantify 24-hour fertilizer-N ammonia loss, closed-flux chambers were installed immediately following 0.15 lbs N (putting green) or 0.2 lbs N per 1000 ft 2 (fairway) treatment applications in July and Sept. 2019. Monthly clipping yields were collected to quantify vigor and fertilizer-N recovery, while semi-weekly use of a multispectral radiometer facilitated canopy dark green color index (DGCI) determination. First year data shows significantly increased bentgrass vigor when urea-based fertilizers were applied in combination with PDSO. Similarly, plots treated with urea- N and PDSO combinations demonstrated increased fertilizer-N recovery. Fertilizer-N ammonia loss 0- to 24-hours following application ranged from 1 to 5% (putting green) or 6% (fairway), depending on urea-N source. Finally, when pooled across urea-N sources, plots treated with PDSO displayed significantly higher DGCI values. Barring very different outcomes in 2020, this thesis will confirm previous PSU research showing improved bentgrass nutrition results from described PDSO treatment. Regarding foliar treatment of putting greens and mitigation of ammonia loss in the meantime, the authors recommend urea be combined with either urease inhibitor or PDSO. Further explanation and guidance forthcoming!